The invention relates to a catheter head for subcutaneous administration of substances, including medically active substances, such as insulin and the like.
A catheter head as known from U.S. Pat. No. 5,522,803 comprises a cannula housing with a cannula and a needle holder, to be connected to the cannula housing, including a feed line for feeding a substance to the catheter head. The cannula projects from the cannula housing and is placed in tissue. In the cannula housing a passage channel to the cannula is formed for the active substance. The cannula housing is designed to allow flush, conforming or mould (or molded) positioning on the surface of the tissue into which the cannula is placed, and it is prepared for being fixed on or attached to the tissue.
A connecting needle is rigidly attached to the needle holder. The connecting needle is introduced into the passage channel of the cannula housing for obtaining a connection. Both the cannula and the cannula housing will stay on the site of attachment in and on the tissue, whereas the needle holder may be repeatedly connected to the cannula housing and separated from the same again. During assembly, the cannula housing and the needle holder are automatically engaging into each other, due to the needle holder detachably anchoring itself to the cannula housing. Guide means are provided for positioning the connecting needle in relation to the passage channel of the cannula housing and for introducing the connecting needle into the passage channel, with the guide means guiding the needle holder at the cannula housing.
The guide means of this known catheter head are formed by a pair of guide pins projecting on either side of the connecting needle and parallel to the same from the needle holder. Accordingly, the cannula housing is provided with guide shafts on either side of an inlet into the passage channel into which one each of the guide pins for introducing the connecting needle is inserted. The connecting needle is positioned in relation to the inlet by the interaction of the guide pins with the guide shafts and guided in centered position during introduction into the passage channel. In the course of advancement of the connecting needle in the passage channel, the needle holder is anchored by an automatically engaging snap-on connection to the cannula housing.